Obesity Programs Have Slim Effect on Kids' Weight

Action Points

A Cochrane review found heterogeneity among interventions targeting obesity in children, but also found that most programs were able to decrease obesity to a degree.

The authors recommended school curriculums focused on nutrition, more time for physical activity in school, better food offerings in school, and a home environment with more physical activity, more nutritional foods, and less screen time.

Obesity prevention programs made children want to eat better and play harder, but they had a limited effect on overall weight control, according to a Cochrane Review meta-analysis.

A review of 55 international studies of programs aimed at reducing childhood obesity found that although most programs were able to reduce adiposity to some degree, not all interventions were effective, reported Elizabeth Waters, PhD, from the University of Melbourne, and colleagues in the Cochrane Database of Systemic Reviews. Children in an intervention group had a standardized mean difference in body mass index (BMI) of -0.15 kg/m2 (95% CI -0.21 to -0.09).

"This review demonstrates wide variation in the effectiveness of individual level and behavioral interventions for childhood obesity prevention," the authors wrote. "On balance, it appears that a variety of interventions can impact on either behaviors or adiposity and shift child outcomes in the desired direction."

Waters' group aimed to update a 2005 review that found many pediatric obesity interventions were not able to reduce weight gain but were successful in promoting a healthy diet and an increased level of physical activity (Cochrane Database Syst Rev 2005; 3).

For the current analysis, data was collected from controlled trials, with a minimum duration of 12 weeks that took place during or after 2005. Studies did not have to be randomized. A total of 36 studies meeting these criteria were added to 19 studies carried over from the previous review.

All participants were younger than 18 at the time the studies began. Nearly 30,000 children were included in the 55 studies.

The majority of the studies were conducted in the U.S. (26), followed by six done in the U.K. Other countries included Canada, the Netherlands, Sweden, Brazil, and Thailand.

For inclusion in this meta-analysis, the studies had to report at least one of multiple primary outcomes including height and weight as well as BMI. Secondary outcomes were activity levels, dietary intake, and change in health knowledge.

Intervention programs were conducted at schools, outside educational settings, and on a community level. Most studies targeted diet and physical activity (21), while others focused on one or the other.

Waters' group found that intervention effects by age subgroups were as follows:

Ages 0 to 5: -0.26 kg/m2 (95% CI -0.53 to 0.00)

Ages 6 to 12: -0.15 kg/m2 (95% CI -0.23 to -0.08)

Ages 13 to 18: -0.09 kg/m2 ( 95% CI -0.20 to 0.03)

The authors also found a high level of observed heterogeneity (I2=82%) among the studies that could not be explained by "randomization status or the type, duration, or setting of the intervention ... the variety of approaches used in the interventions in this review, combined with heterogeneous measures used to assess intervention impacts, limits our ability to draw firm conclusions about the best interventions for effective behavior change."

The authors also acknowledged that possible biases included lack of data from studies with negative findings.

However, they did note that the strongest evidence for the value of intervention programs was in children ages 6 to 12.

Finally, although only a small number of studies looked at whether obesity prevention programs caused any harm, the Cochrane group found that intervention did not lead to negative body image, dangerous dieting, or unhealthy attitudes about weight.

"Governments internationally are being urged to take action to prevent childhood obesity," the authors wrote. They suggested the following strategies showed the most promise:

A school curriculum that emphasizes healthy eating, exercise, and positive body image

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